1. Field of Invention
The present invention relates to a photoelectric element package with temperature compensation. More particularly, the present invention relates to a photoelectric element package with temperature compensation without a header.
2. Related Art
A photoelectric element disclosed in the conventional art is shown in FIGS. 1A-1C. As shown in FIG. 1A, the photoelectric element is mainly constituted by a casing 101 and a header 102, and the casing 101 is fitted on the header 102. In sake of air-tightness required on the conventional photoelectric element package, a process using metal and glass together is adopted in the structure of the header design, such that metal pins can be fixed on the header 102. The metal pins are further connected to a printed circuit board (PCB), such that the electronic elements on the PCB are electrically communicated with the photoelectric element.
As shown in FIG. 1C, a light-emitting element integrated by a laser diode 107 and a photo diode 108 is disposed in a space enclosed by the metal pins above the header, and the photo diode 108 is used to sense the light emitting intensity of the laser diode 107. After the laser diode 107 and the photo diode 108 are soldered to the metal pins above the header by a gold wire, and after the metal pins below the header are connected to an external circuit, electronic signals are transmitted as optical signals through the operation of the photoelectric element.
The space enclosed by the metal pins above the header is limited, and the size of the photo diode 108 is usually larger than that of the laser diode 107, therefore, the size of the header is increased by disposing the laser diode 107, the photo diode 108, and other relevant circuit elements in the limited space. As shown in FIG. 1B, a header 104 has eight pins, and a header 106 shown in FIG. 1C has ten pins. As the size of the header becomes larger, the size of a casing 103 and a casing 105 is also increased, which goes against the miniaturizing development trend of the consumptive products recently.
Furthermore, the conventional art is confronted with the problem in temperature compensation. As shown in FIG. 1A to FIG. 1C, when the photoelectric element is applied in a one-way transmission, the light emitted by the laser diode 107 may be dispersed, and thus the photo diode 108 may not receive the light emitting intensity of a correct ratio. Likewise, when being applied in a dual-way transmission, the light emitting intensity received by the photo diode 108 may include the light emitted by the laser diode 107 and another incident light. Therefore, when the reflected light can not be received correctly, an error may be generated or the compensation cannot be performed correctly if it is intended to perform compensation with the light emitting intensity sensed by the photo diode 108, thereby affecting the transmitted signal intensity.
The further problem lies in energy attenuation of the laser chip caused by the temperature. Therefore, the light emitting intensity of the laser diode 107 decreases as the temperature rises, such that the photo diode 108 senses a weakened intensity, the compensation circuit or the drive circuit may further increase the power of the laser diode 107 so as to increase the light emitting intensity of the laser diode 107, such that the transmitted light signal cannot indicate the actual situation and an error is further generated.